Linear broadening of the confining string in Yang-Mills theory at low temperature

TL;DR

This paper confirms that the confining string in (2+1)-d SU(2) Yang-Mills theory broadens linearly at low temperatures, matching predictions from effective string theory with no extra parameters.

Contribution

It provides the first numerical verification of the linear broadening prediction at low non-zero temperature using precise Monte Carlo data, without introducing new adjustable parameters.

Findings

Logarithmic broadening at zero temperature verified.

Linear broadening at low temperature confirmed.

Excellent agreement between Yang-Mills data and effective string theory.

Abstract

The logarithmic broadening predicted by the systematic low-energy effective field theory for the confining string has recently been verified in numerical simulations of (2+1)-d SU(2) lattice Yang-Mills theory at zero temperature. The same effective theory predicts linear broadening of the string at low non-zero temperature. In this paper, we verify this prediction by comparison with very precise Monte Carlo data. The comparison involves no additional adjustable parameters, because the low-energy constants of the effective theory have already been fixed at zero temperature. It yields very good agreement between the underlying Yang-Mills theory and the effective string theory.